Contronyms: to sanction or to sanction?

This article originally appeared on BoldFace, the official blog of Editors Toronto.

There are some words in English we may not know whether to sanction. They are so impregnated with meaning that their meaning may seem impregnable. If you try to hold them fast, you may find them too fast to hold; at best, you can hope that (of the senses available) one will have left and you will be left with the one that’s left. If, for instance, you ask someone to dust something and find instead they have dusted it, you might understandably lose your temper and have a fit of temper—especially if you are an inflammable, rather than inflammable, kind of person.

How do such self-opposite words—what Jack Herring labelled contronyms—come about? Sometimes it’s because sense and form cleave apart, and sometimes it’s because they cleave together. When they cleave, it’s typically because of a…